Double check your distance, max it out if need be, drop any speed buffs you may have. Regardless the bot is not perfect and will die to this occasionally. I am para 900+ in GG gear, and I only keep my molten core range at 18, but sometimes if theres a item or a craft mat/gem between you and a molten explosion the bot will flip flop back and forth and sometimes it runs too close to the explosion. If you disable gold pickup, set imperial gems only. and turn off mats to legendary only no common+ or magic+ rare+ settings ot greatly educes the chances of this happening. HOWEVER if you are a DH who uses vault/tactical advantage +60% mvspeed etc, you are more likely to get caught in one of these if your bot vaults accidentally trying to wait it out and moves too fast into a kaboom. Awareness usually eats it if its too bad. If your bot purposely walks into these, Then you must have the range set wrong on the class. Or possibly one of the combat misc things unchecked like avoid aoe path around aoe.
